(1) Field of the Invention
The present invention pertains to an improved mounting clip that attaches a circuit component to an electrical device and attenuates vibration of the circuit component and its wiring as the electrical device is operated. More specifically, the present invention pertains to a mounting clip for a thermo-protector that removably attaches the thermo-protector to a switch housing of an electric motor. The thermo-protector is connected to the stator windings of the electric motor. The wiring of the electric motor connected to the thermo-protector is attached to the mounting clip. The mounting clip is provided with a spring mechanism that engages an abutment provided on the switch housing and biases the mounting clip and the attached thermo-protector and thermo-protector wiring away from the switch housing and thereby attenuates vibration of the thermo-protector and its wiring.
(2) Description of the Related Art
Electrical devices, and in particular electric motors, are often provided with thermo-protectors that are connected to the stator winding of the electric motor. The thermo-protector limits the temperature of the electric motor wiring during operation of the electric motor. In this manner the typical thermo-protector protects the wiring of the electric motor, as well as other circuit components of the electric motor, from damage due to excessive heat generated by the current passing through the motor windings.
FIG. 1 shows one illustrative environment of a prior art electric motor 10 having a thermo-protector 12 as a circuit component in the winding of the motor. Because the electric motor 10 and the thermo-protector 12 shown in FIG. 1 are known, they are represented schematically in the drawing figure and only a portion of the motor is shown.
The motor 10 includes a stator comprised of stator laminate plates 14 and magnetic wiring wrapped around the poles of the stator (not shown). The end turns 16 of the stator magnetic wiring 16 are shown projecting from one end of the stack of stator laminate plates 14. An end shield or end cage 18 is also shown in FIG. 1 and a switch housing 22 is shown attached to the end cage.
The circuit component or thermo-protector 12 of the illustrative example has a narrow, box shaped configuration. The thermo-protector is shown connected to a lead 26 of the stator winding. The winding lead 26 is connected to a terminal 28 of the circuit component. A second terminal 32 of the circuit component is connected by a length of wire 34 to a terminal 36 of the switch housing. Additional stator winding leads 38 are connected to other terminals 42 of the switch housing.
The thermo-protector is releasably attached to the switch housing 22 by a mounting clip 44. The mounting clip 44 has an elongate, generally rectangular base 46 and an elongate, generally rectangular support panel 48. The base and support panel intersect each other and give the mounting clip a cross configuration. A pair of resilient flanges 52 project from opposite ends of the base to one side of the base. An attachment hook 54 projects from the opposite side of the base. Each of the flanges 52 have tabs 56 projecting from the flange distal ends. The pair of tabs 56 project toward each other.
The prior art mounting clip 44 is typically constructed of plastic, giving the pair of base flanges 52 a flexibility or resilience. The opposed tabs 56 and the resilience of the base flanges 52 enable the mounting clip 44 to be releasably attached to the circuit component 12 by passing the flanges 52 over opposite sides of the component, with the flange tabs 56 engaging in slots in opposite sides of the circuit component. In this manner, the mounting clip 44 is removably attached to the circuit component 12, meaning that the clip is attached to the component without separate fasteners. By being removably attached to the component, the mounting clip 44 can be easily manually attached and removed from the circuit component 12 without separate fasteners and without damaging parts of the mounting clip.
The support panel 48 of the mounting clip has a pair of wiring clasp assemblies 58 that project outwardly from one side of the panel. The stator winding leads 26, 38 are pressed between the opposed clasps of the two clasp assemblies 58 to removably attach the wiring leads to the support panel of the mounting clip 44 as shown in FIG. 1.
In attaching the circuit component 12 to the switch housing 22 employing the mounting clip 44 of the prior art, the clip 44 is first removably attached to one side of the thermo-protector circuit component 12. The clip is positioned with its flanges 52 adjacent opposite sides of the circuit component 12 and then is pressed onto the component. The clip flanges 52 are caused to flex away from each other and the tabs 56 of the flanges pass over the opposite sides of the circuit component until they engage in the slots (not shown) in the opposite sides of the component. This removably attaches the mounting clip 44 to the circuit component 12.
The clip and component are then assembled to the switch housing 22. The switch housing 22 is provided with a receptacle 62 having an interior volume 64 that is configured to receive at least a portion of the circuit component 12 and the mounting clip 44 attached to the component. A side wall 66 of the receptacle surrounds the interior volume 64. An edge 68 of the receptacle side wall defines a receptacle opening through which the circuit component and attached mounting clip are inserted. The receptacle side wall has a smaller side wall opening 72 at the back of the receptacle interior volume 64 from the receptacle opening. As the component 12 and attached mounting clip 44 are inserted through the receptacle opening and into the receptacle interior volume 64, the attachment hook 54 projecting from the mounting clip base 46 engages in the side wall opening 72 and thereby releasably attaches the circuit component 12 and the mounting clip 44 to the switch housing 22. The stator winding leads are connected to the clasp assemblies 58 as shown in FIG. 1.
The mounting clip 44 of the prior art described above functions well in providing a removable attachment between the circuit component or thermo-protector 12 and a housing of the electric motor 10, specifically the switch housing 22. The releasable attachment of the mounting clip 44 to the circuit component 12 and to the switch housing receptacle 62 enables a quick and easy attachment of the circuit component to the electric motor without the need for separate fasteners. However, during use of the electric motor 10, problems associated with the use of the mounting clip 44 were discovered.
Because the mounting clip 44 is releasably attached or snapped to the circuit component 12 and is then releasably attached or snapped to the receptacle 62 of the switch housing 22, during operation of the motor 10 vibrations from the motor were transmitted to the mounting clip. The vibrations of the mounting clip were also transferred to the stator winding leads 26, 38 held in the clasp assemblies 58 of the mounting clip. The vibration of these leads caused them to rub across each other which at times caused the insulation of the winding leads to wear away, resulting in a short circuit between the leads.
What is needed to overcome the problem with the prior art mounting clip is a means of attenuating the vibration of the clip when the electrical device is operated which in turn will attenuate the vibration of the circuit components and the rubbing together of the circuit component wiring.